The present invention relates to a medico-surgical drainage container and, more particularly, to an urinary drainage means of a type used by persons suffering from certain disease states and recovering from certain forms of surgery of the urethra.
The need for such urinary drainage means arises as a result of the natural build-up of urine in the bladder which occurs on a continuous basis, and cannot be stopped. Accordingly, periodic relief of such build-up of fluid in the bladder is a requirement of any patient, including those resting upon a bed, stretcher or those positioned within a wheelchair.
The prior art of medico-surgical drainage containers, as applicable to the instant invention, is to the best knowledge of the inventor represented by U.S. Pat. No. 4,772,278 (1988) to Baber, entitled Medico-Surgical Drainage Container. Other representative prior art is reflected in U.S. Pat. No. 3,583,401 (1969) to Vallinancourt, entitled Closed Drainage System with Double Lumin Tube; U.S. Pat. No. 4,524,805 (1985) to Hoffman, entitled Normally Closed Duckbill Valve and Method of Manufacture; and U.S. Pat. No. 4,828,554 (1989) to Griffin, entitled One Way Valve for Leg Urinals or the Like.
In the above prior art, said patents to Baber and Hoffman teach medico-surgical drainage containers utilizing a so-called duckbill valve. It is toward the improvement of such medico-surgical containers making use of duckbill valves that the instant invention is directed.
As is, particularly, recognized by Vallinancourt above, a major problem in the operation of a closed urinary drainage system is that the liquid column in the drainage bag will often become static, that is, the tube of the drainage system normally extends downwardly from the level of the patient's bladder to a receptacle some distance lower. The weight of the liquid column will often result in the development of a negative pressure in the bladder, not only emptying it, but also tending to draw the bladder wall against the end of the catheter and even partly into the lumen thereof, with serious adverse effects to the patient. The occurrence of this phenomenon often manifests itself when the bag or collection container of the system is visibly compressed by the ambient atmosphere. During such conditions, the liquid column may on occasion appear to be moving upward toward the patient.
Methods heretofore proposed to alleviate or eliminate this condition include venting the system at a suitable point in its upper portion and the use of abnormally large diameter tubes. As for the latter method, a tube of more than nine millimeters internal diameter will release its liquid column when vigorously shaken and it is believed the tubing larger than thirteen millimeters internal diameter will allow free flow of the liquid as air enters the outlet and bubbles-up through the descending liquid. However, most closed systems actually use tubing in the range of five to twelve millimeters internal diameter and the substitution of larger tubing is not considered practical or convenient.
The entry of air into the lower end of a small single tube is prevented by the surface tens-ion of the liquid column at that point and the fact that there is normally no place for air to enter at the upper end of the tube. A number of prior art systems, including those to Baber and Hoffman above, make use of a duckbill ending to the liquid input to the drainage container in the belief that the configuration thereof will permit appropriate venting within the bag portion to preclude the development of the above described negative pressure in the bladder. It has, however, been determined, over extended usages of such systems, that the desired venting does not always occur, this due to sticking between the respective surfaces of the duckbill valve. When such sticking surfaces of the duckbill valve occurs, the entire venting function thereof is defeated. While the above reference to Hoffman discusses a possible solution to the problem, the inventor herein has determined that through the provision of a wire-like element placed longitudinally within the duckbill valve, the desired venting function of the duckbill and, thereby, suitable operation of the entire system, can be achieved.